The present disclosure relates to ball bats. More particularly, the present disclosure relates to tamper-resistant ball bats. In recent years, composite ball bats have become extremely popular within collegiate-level baseball leagues, men's and women's softball leagues, and related youth leagues. Unlike traditional ball bats featuring solid body constructions made from wood or aluminum, composite ball bats are made from lightweight fibers. As a result, they are much lighter than traditional ball bats and allow a player to achieve an increased bat speed when swinging at a pitch.
Although previously offered composite ball bats have successfully delivered increased power-to-weight ratios, they are highly susceptible to tampering or “doctoring.” Tampering with a composite ball bat commonly entails squeezing the barrel by rolling it between two rollers. In doing so, a player can apply sheer forces that are high enough to delaminate the composite layers. Delamination occurs when the shear stress between composite layers exceeds the strength of the matrix resin. When the internal layers of a composite ball bat delaminate, the bat becomes less stiff and the internal layers take on trampoline-like properties. Increased trampoline-like properties ultimately result in a player being able to hit a ball with greater force.
With previously offered composite bats, delaminations generally occur at or near the center of the layup thickness where the shearing stresses peak. They then propagate along the fibers in such a way that they remain hidden below the surface of the bat. Because internal delaminations do not show any visible damage to the surface of a bat, it is easy for players to secretly tamper with previously offered composite bats. Rampant cheating amongst ball players at any skill level damages the integrity of the sport and can leave lasting negative impressions on participants. The sports industry needs an improved composite bat that is less vulnerable to concealable tampering.